Help picking between 2 telephoto lenses

[Neb]

Hey everyone, I'm new to the site and fairly new to photography. I'm trying to chose between 2 telephoto lenses. Right now I've got the 400D body with the Canon EF-S 17-55 F2.8 IS lens which is great. But I need something to people at different events.. I won't always be using a tripod so that's why I'm having difficulty choosing what telephoto lens to get. I need something that's nice and crisp as well.. Here's the 2 that I'm looking at:

Both in the same price range, but the f4 has IS where the f2.8 doesn't.. thoughts?

CANON EF 70-200MM/2.8 L AF USM

OR

CANON EF 70-200 F4 L IS ZOOM LENS

 

[Big Mike]

Welcome to the forum.

Either lens will be very sharp and have great image quality. No problems there.

On one hand, you probably get two or three stops worth of 'hand-hold-ability' with the IS, while there is only one stop difference between F4 and F2.8. But on the other hand, IS does nothing to freeze moving subjects.
So if you are thinking that you will primairly shoot moving subjects, I'd suggest the F2.8 version....but if you are shooting subjects that don't move as much, then you will probably get more benefit from the F4 IS version.

Another concern might be the weight. I believe the F4 IS, is a fair bit smaller and lighter than the F2.8 version...which might important if you are shooting with it all day, or even because you have the 400D, which is a small, light camera and might be out of place with the heavier lens.

Ideally, I'd recommend you stretch the budget and just get the F2.8 IS lens. Then you have the best of both worlds (except on the weight issue). Also, if you get this one, you will always know that you bought the 'best' tool avalaible and won't need to second guess your choice when you find yourself in a situation that requires either a wider aperture or IS etc. That's what I did...and I love my F2.8 L IS

 

[Neb]

Do you mean this one?

Amazon.com: Canon EF 70-200mm f/2.8L IS USM Telephoto Zoom Lens for Canon SLR Cameras: Camera & Photo

Or is there a newer version out?

 

[bigtwinky]

Thats the one Mike was referring to.

A bit more expensive, but worth the investment.

I'd probably lean towards the f/4 IS myself, but I do alot of walking around and weight is more of an issue.